While liquid or creamy hair dye compositions have been widely used so far, it is difficult to apply these compositions to the head hair evenly. In particular, in the case of consumers themselves applying a hair dye composition to their own head hair at the roots or on the back of the head, they need to acquire skills of, such as, “blocking” or using two mirrors facing each other (“two-mirror technique”), and a careful operation is required to apply the composition evenly.
Accordingly, discharging a composition as foam in order to simplify the hair dyeing operation has been proposed, and hair dyes of a two-part aerosol type and those of a one-part non-aerosol type are known, for example. However, those of a two-part aerosol type have such problems that uneven bleaching or uneven dyeing is likely to occur due to an inconsistent mixing ratio of a first part and a second part, a pressure-proof metal container or the like is oxidized and corroded by hydrogen peroxide, and the internal pressure of the pressure-tight container is excessively increased by degradation of hydrogen peroxide. Furthermore, since such a one-part non-aerosol type has no or weak bleaching ability, it is difficult to achieve a great change in the color tone by one procedure. Therefore, a problem arises, i.e., a hair dyeing operation tends to be cumbersome since a hair dye is required to be left to develop for a long time and the procedure is required to be repeated after application.
On the other hand, discharging a two-part hair dye composition as foam from a non-aerosol type foamer container (e.g., Patent Documents 1 and 2) has been proposed. By discharging a mixture solution of a first part and a second part from a foamer container as foam, variation in the mixing ratio hardly occurs compared to conventional two-part aerosol hair dyes and a sufficient bleaching or hair dyeing ability may be obtained compared to conventional one-part non-aerosol hair dyes.
Meanwhile, all of these two-part aerosol type hair dyes, one-part non-aerosol hair dyes and two-part non-aerosol hair dyes, by which the hair dyes are discharged as foam from foamer containers, still suffer a common problem, i.e., it is difficult to adjust foam quality by which easiness of discharging from a container and operability on the head hair are well-balanced. To solve this problem, for example, Patent Document 3 proposes a composition that maintains adequate foam quality and has an excellent foam breaking property at the time of application to the hair. However, a careful operation is still required for even application, and an alternative dyeing method has been needed.    [Patent Document 1] JP-A-2004-339216    [Patent Document 2] JP-A-2006-124279    [Patent Document 3] JP-A-2001-019626